Sign Others' GPG Key

gistfile1.md

# pull the key from the remote key server
$ gpg [--keyserver keyserver.ubuntu.com] --recv-keys <remote_key_id>
 
# sign the key
$ gpg --sign-key <key_id>
 
# if there are multiple local keys, use a different local secret key for signing
$ gpg --local-user <local_key_id> --sign-key <remote_key_id>
 
# confirm that the key is signed
$ gpg --list-sig <remote_key_id>
 
# export and encrypt remote key
$ gpg -a --export <remote_key_id> | gpg -se -r <remote_key_id> > <remote_key_id>.asc.gpg

If signer pushed the signed key directly to key server, we can import the remote signed key back into our local keyring by downloading the pub key from the key server's web interface, then run:

gpg --import ef6baa3efda9b3fcc76f0f8ca33d0d43109616c9.asc